Scientists crack tree’s genetic code

Researchers for the first time have deciphered the genetic code of a tree, which could lead to new varieties better at producing wood, paper and fuel.

The work could vastly increase cultivation of the black cottonwood, a fast-growing poplar already used by the timber and paper industries. Details of the analysis of the tree’s DNA, performed by dozens of researchers in eight countries, appear this week in the journal Science.

Today, the black cottonwood is still considered “wild,” even though it’s grown for lumber and pulp. Fifteen years from now, fully domesticated varieties of the tree, optimally tuned to grow faster and longer, better resist insects and disease and require less water and nutrients, could be growing on tree farms across the U.S., researchers said.

To create such poplars, researchers first must hunt among the tree’s more than 45,500 genes to understand how they control its growth. Doing so can allow later tinkering, including selective breeding and genetic manipulation to bring out desirable traits. Already, they have found 93 genes associated with the production of cellulose and lignin, which form the walls of plant cells.

One goal is to create a poplar variety that can be used as a source of ethanol, which can be burned as fuel. Ethanol is more expensive and difficult to produce from wood than it is from crops such as corn.

Researchers also would like to create poplar varieties to soak up even more carbon dioxide from the atmosphere and lessen the effect of the gas on global warming.

The black cottonwood is the third plant, after rice and a weed called Arabidopsis thaliana, to have its genome sequence published. Comparing their respective genomes is expected to shed light on their separate evolutionary paths, researchers said.

The team isolated the sequenced DNA from a poplar tree growing along the Nisqually River in Washington state.

More than three dozen researchers from the U.S., Austria, Belgium, Canada, Finland, France, Germany and Sweden were led by Gerald Tuskan of Oak Ridge National Laboratory in Tennessee.